Although Canada gained the first-mover advantage after federally legalizing recreational marijuana back in October, the United States presently holds the largest market share. Combined, the North American legal cannabis market hit $12 billion last year, and analysts forecast that the market will reach $25.5 billion by 2021, according to a report by Cannabis Business Plan. The North American Marijuana Index, which tracks the leading cannabis stocks operating in the U.S. and Canada, has gained 33% year to date. The index’s top 5 holdings by market cap include: Canopy Growth Corp. (CGC) (WEED)Aurora Cannabis Inc (ACB)Tilary Inc. (TLRY)GW Pharmaceuticals Plc (GWPH)Cronos Group Inc. (CRON) As marijuana industry continues to show strength and the sentiment surrounding stocks in the sector remain positive, investors continue to place their bets on marijuana stocks.Could These Marijuana Stocks Grow Your Portfolio?